Search for a string (SUBSTRING) into another string in C

#include <stdio.h>
#include <conio.h>
#include <string.h>
#include <windows.h>
int xstrsearch ( char *, char * ) ;
void show( ) ;
int main( )
{
 char s1[ ] = "NagpurKicit" ;
 char s2[ ] = "Kicit" ;
 int pos ;
 system ( "cls" ) ;
 printf ( "String s1: %s\n\n", s1 ) ;
 printf ( "String s2: %s\n\n", s2 ) ;
 /* search if s2 is present in s1 */
 pos = xstrsearch ( s1, s2 ) ;
 printf ( "The pattern string is found at position: %d\n", pos ) ;
 return 0 ;
}
/* searches for the given pattern s2 into the string s1 */
int xstrsearch ( char * s1, char * s2 )
{
 int i, j, k ;
 int l1 = strlen ( s1 ) ;
 int l2 = strlen ( s2 ) ;
 for ( i = 0 ; i <= l1 - l2 ; i++ )
 {
  j = 0 ;
  k = i ;
  while ( ( s1[k] == s2[j] ) && ( j < l2 ) )
  {
   k++ ;
   j++ ;
  }
  if ( j == l2 )
   return i ;
 }
 return -1 ;
}